3D Flash Memory Dummy Word Line Voltage Generators
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Solution Overview
Problem
Three-dimensional (3D) flash memory devices experience increased program disturbance effects due to electric field differences between the boosted channel of program inhibit cells and the bit line or common source line.
Innovation Solution
The implementation of a 3D flash memory device with a specific configuration, including a first cell string with a program cell and a second cell string with a program inhibit cell, along with first and second dummy word lines with different configurations, helps reduce electric field differences and mitigate program disturbance effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If 3D flash memory is used to overcome integration limits, then integration performance is improved, but program disturbance effects increase
Solution Approach 1:
Dummy word lines are introduced as intermediary elements between the ground select line and main word lines, and between string select lines and uppermost main word lines. These dummy word lines act as mediators to equalize electric field distributions, thereby reducing program disturbance effects while maintaining the benefits of 3D vertical channel structure for high integration
2Reliability
If dummy word lines are added to reduce electric field difference, then program disturbance is reduced, but device complexity increases
Solution Approach 1:
Dummy word lines are strategically placed only at specific locations where electric field imbalance occurs - between ground select line and lowermost main word line, and between string select lines and uppermost main word lines. This localized approach addresses the specific problem areas without uniformly increasing complexity throughout the entire device structure
Data Source
AI summary
A three-dimensional (3D) flash memory includes a first dummy word line disposed between a ground select line and a lowermost main word line, and a second dummy word line of different word line configuration disposed between a string select line and an upper most main word line.